Catnip (Nepeta cataria)

Cat-lovers have often witnessed the erratic behavior of their pets when under the influence of having eaten catnip, a substance that seems to affect them in the manner that marijuana changes human behavior.

An animal behavior expert at the University of California School of Veterinary Medicine explains: The active substance of catnip is a chemical called nepetalactone, which sets off in the cat's brain various stimuli leading to pleasure.

The cat's out of the bag: Catnip (Nepeta cataria) is 10 times more effective for keeping mosquitoes at bay than DEET, the chemical compound used in most conventional bug repellents. Iowa State University entomologists first discovered that nepetalactone, the essential oil in the feline-friendly herb, sent cockroaches packing. In August, the same researchers revealed that the natural compound--distilled from catnip--makes mosquitoes buzz off in a big way, too.